1. Field of the Invention
The present invention generally relates to digital gauges and more specifically to a digital air or gas manifold gauge having integral pressure-temperature algorithms and a rotatable display means.
2. Description of Related Art
In the field of HVAC (heating, ventilation, and air conditioning) there is a marked need for devices to provide readouts at various points in HVAC systems in order to monitor and assess performance of same. Typically, an HVAC servicer is interested in identifying the pressure, temperature and other operating conditions of the various liquid and gas flows throughout the systems. This includes the temperature and pressure of the refrigerants and propellants as well as the heated, cooled, or ventilated air.
A typical refrigerant gauge comprises a Bourdon tube mechanical-type gauge that provides a plurality of analog scales on single gauge in order to show the saturation temperature for various refrigerants given the reading of the pressure by the gauge. These gauges therefore utilize a set conversion from pressure detection to temperature readout. The disadvantage of these traditional devices is that accommodating a multiplicity of refrigerants on a single gauge makes the increasing number of scales difficult to read. Consequently, a user has to choose a mechanical gage limited to the refrigerants he normally uses. As the number of refrigerant options increases this becomes a limiting factor requiring, more often than not, the purchase or multiple manifold gauges to cover a mechanic's range of daily jobs.
Many manufacturers have offered the industry the option of using digital techniques to display pressure accurately and conveniently in a manifold formatted gage. However, in the case of these digital gages, the display of the corresponding saturation temperatures for various refrigerants has been neglected, severely limiting the usefulness of the devices. Furthermore, the majority of these devices are provided in the form of a handheld device having a plurality of wires extending therefrom, which can be unwieldy and inconvenient to use, particularly in tight spaces.
The reason for providing the pressure-temperature (P-T) relationship for various refrigerants on the face of a digital gage is to allow the service technician to charge an AC system accurately using the superheat specification for the system and/or to diagnose it using the sub-cooling settings provided by the manufacturer. This function requires, in addition to the saturation temperature information, the measurement of temperature at specific points in the AC system concurrent to the measurement of pressure at similarly specific points in the system. There have been many attempts at providing improved digital manifold gauges for refrigerant and other HVAC systems, however none have adequately address the usability and convenience factors that the present invention addresses.
It is, therefore, to the effective resolution of the aforementioned problems and shortcomings of the prior art that the present invention is directed. However, in view of the digital manifold gauges in existence at the time of the present invention, it was not obvious to those persons of ordinary skill in the pertinent art as to how the identified needs could be fulfilled in an advantageous manner.